Hydraulic valve tappet



27, 1959 E, L, DAYTON 2,870,755

v HYDRAULIC VALVE TAPPET I Filed May 14, 1956 ,mms/WOR.r

ERNEST l.. DAYTON MLMWM? ATTORN EYS Unired ,States HYDRAULIC VALVETAPPET Ernest L. Dayton, Detrhit, Mich.

Application May 14, 1956, Serial No. 584,732

Claims. (Cl. 12S- 90) This invention relates to an improved hydraulicvalve tappet assembly of the type suitable for use in connection ywithinternal combustion engines.

Hydraulic tappet assemblies, as used in internal combustion engines areusually supplied with oil supplied from the lubricating system of theengine and function to take up clearance between the valve push rods and-tappets automatically as soon as such clearance exists.

The specic structure of hydraulic valve tappets varies considerably but,in general, comprises a cylinder and a tubular plunger or pistonslidably supported in the cylinder. When installed, the bottom of thecylinder is usually engaged by a cam on the camshaft of the engine andthe top of the piston is closed by a plug which ordinarily engages thevalve operating push rod of the engine.

Also, an adjusting chamber is normally provided in the cylinder belowthe piston and the bottom of the piston has a valve controlled portcommunicating with the adjusting chamber. Hydraulic iluid, such as oil,is admitted to the adjusting chamber through the valve controlled portin the piston and the clearance between the piston and push rod is takenup by the column of oil below the piston.

One object of this invention is to provide a hydraulic tappet assemblythat incorporates a gravity system for supplying oil thereto toreplenish the column of oil in the adjusting chamber.

Another object of the invention is to provide a t-appet vassembly inwhich the plug closing the upper end of the piston is provided with anopening therein into which the push rod extends for engagement with anabutment within the piston, and in which the oil is gravity fed to theassembly by running down along the push rod and into the hollow interiorof the piston.

The tappet assembly o-rdinarily will rotate at a very high speed aboutits axis due to the engagement of the cam with the bottom of thecylinder. This occurs because it is practically impossible to arrangethe parts so that the cam always engages the bottom of the cylinderprecisely at its center. As a result, the oil entering the piston viathe push rod is apt to be thrown radially outwa'rdly by the rapidlyrotating assembly so that only a small fraction of the oil actuallyenters the hollow piston. Accordingly, a further object of the inventionis to provide a gravity fed tappet assembly in which provision is madefor preventing the oil from being thrown off laterally by the rotatingtappet assembly.

There is also a tendency for oil Within .the piston to be thrown outthrough the opening in the upper end of .the piston as a result of thelongitudinal reciprocation of the tappet assembly by the cam. Stillanother object of the invention is to provide means for preventing theoil within the piston from being thrown out by the reciprocation of thetappet assembly.

Other objects of the invention will become apparent vas the followingdescription proceeds, y especially when consideredwith the accompanyingdrawing, wherein:

Figure l is a sectional view of a portion of an internal ice combustionengine showing a valve operating lnkageincluding the tappet assembly,constructed in accordance with the invention.

Figure 2 is an enlarged longitudinal sectional view of the tappetassembly.

Figure 3 is a detailed perspective view of the plug for closing theupper end of the piston.

Figure 4 is a detailed plan View of the ball Valve retainer.

Figure 5 is a fragmentary longitudinal sectional view illustrating amodification.

Referring now more particularly to the drawings, and especially toFigures 1-4 thereof, the numeral 10 designates generally the frame of aninternal combustion engine having one or more cylinders 11 in each ofwhich is litteda reciprocating piston 12. Reciprocably mounted in thecylinder head 14 above the piston 12 is a poppet valve 16 which, inconventional manner, controls the inlet or exhaust for the cylinder 11.The valve 16 is normally held in the closed position illustrated by thevalve spring 18, and during engine operation is intermittently moveddownwardly to its open position in opposition to the spring by the valveoperating cam 210 whose motion is transmitted to the upper end 22 of thevalve through the hydraulic tappet assembly 24, push rod 26 and valverocker 2S. 'l'he valve rocker 28 is rotatably supported on the shaft Eiland has an arm 32 bearing upon the upper end 22 of valve 16, and asecond arm 34. The arm 34 carries a depending part 36 which may be ofnon-circular cross-section and which tits into a recess in the upper endof the push rod 26, the recess having a similar non-circularcross-section. Thus, the part 36 is removably received in the recess ofthe push rod and the push rod cannot rotate relative to the projectiondue to the non-circular cross-section of the interconnecting parts. Thepart 36 is rigidly connected to the arm 34 of the rocker so that itcannot rotate.

The tappet assembly 24 comprises a cylinder 3S and a piston itlsupported within the cylinder for sliding movement. The cylinder 38 is,in turn, slidably mounted in t a vertically extending bore 42 of theengine frame 10,

and the bottom of the cylinder is closed by a Wall 44. The bottomsurface of the wall 44 forms a bearing for engagement with the cam Ztl.The top of cylinder 38 is open for receiving the push rod 26, and, ofcourse, the piston is assembled inthe cylinder by inserting it throughthe open top of the cylinder.

The piston d@ is tubular in cross section and the top of the piston isclosedifby a plug 46. The plug 46 comprises an annular body member 48having a skirt portion 5th which extends into the upper end of thepiston in a close sliding iit. The body member 48 has an annular flange52 above the skirt portion which extends laterally outwardly therefromand rests upon the upper end of the piston. A tubular sleeve v54 extendsthrough the body member andis rigidly secured therein. The sleeve has aninternal diameter somewhat greater than the diameter of the push rod andit extends upwardly from the body member for a substantial distance, asseen in Figure 2. The sleeve extends for avconsiderable distance belowthe body member 43 and the lower end of the sleeve is closed by atransverse wall 56. The sleeve is formed with a pair of diametricallyopposite apertures 58 between the body member and thetransverse wall 56.The lower end 60 of the push rod is rounded and bears upon a concaverecess inthe upper surface of the transverse wall 56, the transversewall thus providing ,an abutment for the lower end of the push rod. Theplug 46 and sleeve 54 can be of one-piece construction if desired.

The internal diameter ofthe cylinder 38 is yreduced at the bottom toprovide an adjusting chamber or oil reservoir 62y and alsoto provide aninternal annular shoulder 63 for engaging the bottom of the piston 40 inthe leakl down or collapsed position of the piston within the cylinder.As shown in Figure 2, the bottom of the piston has a p'ort164` whichestablishes communication between the adjusting chamber 62'and the spaceor chamber 66 Within the piston.

i I The transfer of oil through the port 64 is Controlled by the pistonand the retainer 72 .holdstheball normally to enable movement of theball by the action of' gravity to its open position. The retainer 72iscup-shaped ami has a cylindrical wall l71'3 vand a frusto-conical wallextending beneath the cylindrical wall in continuation thereof whichdenes a central opening 82. The upper end of the tubular wall portion 78is turnedl radially outwardly to provide a flange 84 engageable with theunderside of the piston and also engageable by the upper end of the coilspring 74 which has its lower end seated on the bottom wall 44 ofcylinder 37. The piston has an annular extension 86 which surrounds theport and loosely receives the cylindrical portion of the retainer tocenter it. The coil spring 74 is held under compression between theiiange 84 and wall 44 andV is of sufficient strength to hold theretainer 72 in place on the piston 40 throughout the extent of movementof the latter. The coil spring 74 also tends to maintain the piston inthe extended position of Figure 2, in which the ball 70 is rmly seatedby the pressure of oil beneath the piston, during normal operation ofthe tappet, but is not of sufiicient strength to prevent movement of thepiston to its lowermost or leak-down position in which the lower end ofthe piston engages the shoulder 63 within the cylinder Vwhen operationof the engine is discontinued.

not restrict the flow of lubricant through the retainer.`

The axial spacing between the bar 88 and the seat 76 is accuratelypredetermined with respect to the diameter of the ball member 70. Inpractice, the bar is located so as to afford a predetermined maximumclearance between the seat 76 and the ball member 70 in the openposition of the latter. It is important to the satisfactory operation ofthe tappet assembly to limit the clearance between the ball member andseat to approximately ve to seven thousandths of an inch. It will benoted that the bar extends transversely of the opening 82 and is locatedslightly beneath the latter so that the bar may be properly positionedby inserting a feeler gauge or pin between the ball and the bar 88 andthereafter adjust the bar until the ball is rmly engaged with the seat.Since the bar 88 is connected at one end only, the feeler gauge may beinserted from a great many angles without diticulty and much moreconveniently than if the bar were connected at both ends to theretainer.

as to lubricate the valve rocker with oil supplied from the lubricatingsystem of the engine to the passage through the hollow shaft 30. Apassage 93 in the valve rocker extends from the annular groove and opensin a position adjacent to the projecting part 36 to supply oil from thegroove to the connection between the part 36`and the recess in the upperend of the push rod. Theoil thus appliedrwill not only lubricatethepjoint at the upper end of the push rod but will run down the outersurface of the push rod during the operation of the engine and will flowinto the piston chamber 66 through the sleeve 54 and apertures Setherein. Thus, a reservoir of oil will be maintained in the pistonchamber 66 to be supplied to the adjusting chamber 62 in the cylinder toreplenish the column of oil therein as required. While it is preferredto have the oil run down the exterior surface of the push rod, the pushrod might also be formedto have a longitudinal passage with a port atYthe upper end having a lip or the like to receive oil from passage 93and a port at the lower end beneath plug 46 for delivering the oil tothe piston chamber. f f

Due to the fact that it is practically impossible to obtain Va precisedead center engagement of the cam 20 with the lower end of the cylinder,the cylinder and hence the kpiston 40 and plug 46 will ordinarily becaused to rotate at very high speeds depending upon the speed of theengine. There is a tendency for the oil, as it flows down the push rod,to bridge the gap between the opening at the upper end of the sleeve andflow in a thin film across the upper end of the rotating sleeve and tolbe thrown laterally outwardly by the rotation thereof. This tendency isincreased by the viscosity of the `oil, the speed of rotation of thetappet assembly and the size of the opening in the upper end of thesleeve relative to the push rod through which the latter extends.However, I have found that by providing the sleeve 54 of substantiallength to elongate the opening through the plug, the oil owing along thepush rod within the sleeve will form a cohesive tubular column which, byreason of its weight will flow downwardly within the sleeve and drawwith it the oil on the push rod above the sleeve and thereby resist anytendency of the oil to escape. The effectiveness of the annular columnof oil to perform this function depends in part at least upon the lengthof the sleeve. It is apparent that if the sleeve were omitted, theeffectiveness of the annular column of oil to perform this functionwould be greatly diminished due to the fact that the opening through theplug would be relatively short, and thus a great deal of oil would belost. Moreover, the transverse surface at the upper end of the elongatedsleeve 54 is of a relatively small radial dimension as compared with thetransverse surface at the top of the body member 4S. Accordingly, anyoil that might splash onto the upper end of the sleeve and thrownradially outwardly thereby will have little or no tendency of drawingother oil from Vthe push rod with it. Assuming no sleeve and the pushrod extending through the body member opening, any loil splashing ou theupper surface of the body member would tend strongly to draw other oilwithit due to its extended radial dimension and also tothe greaterperipheral speed of the radially outer portions of this surface.

There is also a tendency for the oil within the piston to splash aboutduring the reciprocation of the tappet when the motor is in operation.However, by providing the transverse abutment wall 56 and the lateralapertures 58, the abutment surface being disposed directly beneath theopening into which the push rod extends, oil cannot pass from the pistonchamber through the sleeve in a direct line and, hence, little or no oilis lost by splashing within the piston chamber during reciprocation ofthe tappet assembly.

The push rod will not rotate with the tappet assembly because of itsnon-rotatable connection with the part 36 on the valve rocker. However,sometimes a rotatable connection is` provided between the push rod andvalve rocker so that the push rod may be rotated by the tappet assembly.However, even if the push rod does rotate,

-there is little tendency to throw oil because of its relatively smalldiameter, and hence'its relatively low peripheral speed.

Figure 5 illustrates a modification. The tappet assembly 99y of Figure 5differs from that previously described in that theAretainer 72 isomitted and the bar 88' s car- Lrieddirectly by the piston. The bar 88has a depending `part A100 theupper end of which is welded to or other-Wise permanently secured to ie annular extension 86, and atransversepart 102 disposed beneath the ball 70. The ,part 102 is located so as topermit the desired clearance between the ball and seat in the leak-downposition while at the same time retaining the ball is assembled relationwith the piston. Otherwise, the tappet assembly 99 is exactly like theone shown in Figures l-4 and may be substituted therefor in thearrangement of Figure 1.

What I claim as my invention is:

1. A hydraulic tappet assembly for a valve comprising a generallyupright cylinder having a closed lower end providing a chamber forhydraulic lluid and having au open upper end, a piston mounted in saidcylinder for longitudinal sliding movement `between a collapsed positionadjacent the lower end of said cylinder and an extended position spacedaxially from the lower end of said cylinder, a chamber within saidpiston, a port in the lower end of said piston connecting said pistonchamber with said cylinder chamber, an opening into said piston chamberthrough the upper end of said piston, means providing a connectionbetween said valve and said piston including an upright push rod havingits lower end extending into the open upper end of said cylinder andthrough said `opening into said piston chamber, said push rod beingsubstantially smaller in cross section than said opening and spacedinwardly from the boundary thereof, means within said piston chamberproviding an abutment for the lower end of said push rod, means withinsaid chamber providing a lateral aperture above said abutment andopposite the lower end portion of said push rod for passage of fluidthrough said opening into said piston chamber, and means for supplyinghydraulic fluid to said push rod above said piston for gravity ow downsaid push rod into said piston chamber through said lateral aperture,said abutment being spaced directly beneath said opening tosubstantially prevent hydraulic fluid in said piston chamber frompassing out through said opening along a straight path duringreciprocation of said tappet assembly.

2. The tappet assembly defined in claim l in which the hydraulic liuidis supplied to the exterior surface of said push rod by said supplyingmeans, and a sleeve surrounding said opening and extending upwardly fromthe upper end thereof loosely receiving said push rod to prevent theloss of hydraulic fluid flowing down said push rod.

3. A hydraulic tappet assembly for a valve comprising an uprightcylinder having a closed lower end pro viding a chamber for hydraulicuid and having an open upper end, a piston mounted in said cylinder forlongitudinal sliding movement between a collapsed position adjacent thelower end of said cylinder and an extended position spaced axially fromthe lower end of said cylinder, said piston being hollow to provide achamber and having a port in the lower end thereof connecting saidpiston chamber with said cylinder chamber, valve means controlling theliow of fluid through said port, a cap closing the upper end of saidpiston and having an opening therethrough into said piston chamber,means providing a connection between said valve and said pistonincluding an upright push rod having its lower end extending into theopen upper end of said cylinder and through said opening into saidpiston chamber, said push rod being substantially smaller incross-section than said opening and spaced inwardly from the boundarythereof, said cap having a depending part extending into said pistonchamber, said part being formed with a transverse abutment at the lowerend engageable by the lower end of said push'rod, said abutment beingspaced directly beneath said opening to substantially prevent hydraulicfluid in said piston chamber from passing out of said piston chamberthrough said opening in a straight path during reciprocation of saidtappet assembly, said part also having lateral apertures above saidabutment and opposite the lower end portion of said push `rodforthepassage of uid through said opening rinto .said vpiston chamber, andmeans for supplying hydraulic fluid onto the exterior surface of saidpush rod above said piston for gravity flow along said push rod intosaid piston chamber through said lateral apertures.

4. The tappet assembly defined in claim 3 in which said connectionbetween said piston and the valve includes a valve rocker engaging theupper end of said push rod, and said hydraulic liuid supplying meansincludes a passage in said valve rocker opening adjacent to-.Said pushrod for supplying hydraulic uid to the latter.

5. The tappet assembly defined in claim 3 including an elongated sleeveon said cap surrounding said opening and extending upwardly from theupper end thereof loosely receiving said push rod to prevent the loss ofhydraulic fluid owing down .said push rod.

6. The tappet assembly defined in claim 3 in which said valve meansincludes an annular valve seat surrounding said port at the side thereoffacing the closed end of said cylinder, a ball valve member supported4in a position to .engage said valve seat in response to an increase inpressure in said cylinder chamber, and a retainer for said ball .Valvemember including a bar extending across said ball valve member beneaththe latter and attached at least at one end for movement as a unit withsaid piston, said bar being located beneath all portions of said pistonto enable the lateral insertion of a feeler gauge between said ballvalve member and bar without interference with said piston.

7. The tappet assemblyv defined in claim 6 in which y one end only ofsaid bar is attached to further avoid interference during lateralinsertion of a feeler gauge, said one end being attached directly tosaid piston.

8. The tappet assembly defined in claim 3 in which said valve meansincludes an annular valve seat surrounding said port at the side thereoffacing the closed end of said cylinder, a ball valve member supported ina position to engage said valve seat in response to an increase inpressure in said cylinder chamber, and a retainer for said ball valvemember, said retainer comprising a generally cup-shaped annular memberhaving an opening in the bottom and movable as a unit with said piston,said ball valve member being located in said annular member and theopening through the latter being of greater diameter than said ballvalve member, and a bar extending partway across the opening throughsaid annular member in a position to engage and retain said ball valvemember in said annular member, one end only of said bar being integrallyconnected to said annular member at the edge of the openingtherethrough, the remaining portions of said bar being free fromconnection with and spaced from said annular member said bar beinglocated beneath all portions of said piston and beneath the bottom ofsaid annular member to enable the lateral insertionof a feeler gaugebetween said ball valve member and -bar without interference with saidpiston or annular member.

9. A hydraulic tappet assembly for a valve comprising a cylinder closedat one end to a chamber for hydraulic duid, a piston mounted in saidcylinder for longitudinal sliding movement between a collapsed positionadjacent the closed end of said cylinder and an extended position spacedaxially from the closed end of said cylinder, a passage in said piston,a port in the end of said piston adjacent the closed end of saidcylinder connecting said passage and chamber, means for supplyinghydraulic fluid to said passage, valve means controlling the flow ofhydraulic fluid through said port including an annularseat surroundingsaid port at the side thereof facing the closed end of said cylinder, aball member supported in a position to engage said seat in response toan increase in pressure in said chamber, and a retainer for said ballmember, said retainer comprising a generally cup-shaped member having anopening in the bottom and movable as a unit with said piston,

said ball member being located in said annular mem-ber 'and the openingthrough the latter being of greater diameter than said ball member, anda bar extending partway across the opening through said annular memberin a position to engage and retain said ball member inv said i annularmember,'one end only of said bar being integrally connected to saidannular member at the edge of the opening therethrough, the'remainingportions of said bar being free from connection with and spaced fromsaid annular member, said bar being located beneath all portions of saidpiston and beneath the bottom of said annular member to enable thelateral insertion of a feeler gauge between said ball valve member andbar without interference with said piston or annular member.

i 10. A hydraulic tappet assembly for a valve comprising a generallyupright cylinder having a closed lower end providing a chamber forhydraulic fluid and having an open upper end, a piston mounted in saidcylinder for longitudinal sliding movement between a collapsed positionadjacent the lower end of said cylinder and an extended position spacedaxially from the lower end of said cylinder, a chamber within saidpiston, a port in the lower end of said piston connecting said pistonchamber with said cylinder chamber, an opening into said piston chamberthrough the upper end of said piston, means providing a connectionbetween said valve and said piston including an uprighty push rod havingits lower end extending into the open upper end of said cylinder andthrough said opening into said piston chamber, said push rod beingsubstantially Vsmaller in cross section than said opening and spacedinwardlyfrom the boundary thereof, means within said piston chamberproviding an abutment for the lower end of said push rod, means withinsaid piston chamber providing a lateral aperture above said abutment andopposite the lower end portion of said push rod for passage of uidthrough said opening into said piston chamber, means for supplyinghydraulic ud to the exterior surface of said push rod above said pistoufor gravity flow down said push rod into saidr piston chamber throughsaid lateral aperture, and an elongated sleeve surrounding said openingand extending upwardly from the upper end thereof loosely receiving saidpush rod to prevent the loss of hydraulic uid owing down said push rod.

ReferencesCited in the ile of this patent UNITED STATES PATENTS2,250,752 Dayton July 29, 1941 2,724,373 Dolza Nov. 22, 1955 2,752,901Bergmann July 3, 1956 2,755,785 Oldberg July 24, 1956

